The quality of a video sequence or of a still image may vary widely depending on the source. For example, computer-generated content may be of the highest quality. Packaged media content, for example, Blu-ray media, may be of relatively high quality. Over-the-air high-definition (HD) broadcast content may be of relatively intermediate quality, while content distributed via cable and satellite, may be of a relatively lower quality. Internet protocol television (IPTV) and streamed content may be of relatively low quality. Methods and systems for video and image enhancement that automatically adapt to image- or video-content quality may be desirable. Additionally, methods and systems for automatic estimation of an additive noise in an image or in a video sequence may be desirable.